Eastern European member states could push for changes to the European Union's fundamental Lisbon Treaty to strengthen members' sovereign powers if Hungary wins clear victory in the October 2 referendum on rejecting migrant quotas, Reuters reports today.

Citing the daily newspaper Nepszabadsag, the report suggests that Hungary's stance on migration and building border fences has cemented support for the government's ruling Fidesz party.

Nepszabadsag said if more than half of Hungary's eight million voters cast a valid vote in the referendum, likely to show strong support for the government, the prime minister, a key figure in a eurosceptic alliance of ex-communist, eastern European states, could use the momentum to bolster his efforts to rein in Brussels.

The report, which did not name its source, said Hungary could propose exempting national migration rules from common European policies, trouncing any scheme to share responsibility for migrants among EU member states. It gave no further details.

When asked about the unnamed report, Government Spokesperson Zoltán Kovács said in an emailed response:

"There is no change in the prime minister's stance ... that several fundamental circumstances have changed since the Lisbon Treaty, which Europe had not been prepared for," such as Britain leaving the bloc or the migrant crisis.

"This would justify talking about the Treaty as well," the spokesman said. "However, (the prime minister) has also said that Hungary alone was too small and not powerful enough to initiate or implement something like this."

The 2009 Lisbon Treaty set out the economic and political framework of the EU, created the office of a permanent president and enhanced the powers of the European Parliament.

European leaders meeting in Bratislava without Britain last week agreed to present new plans for reinvigorating the EU by March. Budapest and Warsaw are calling for Brussels to return more powers to EU member states.

There has been tension between German Chancellor Angela Merkel and ex-communist eastern states, which have refused to take in asylum-seekers, while Germany nearly unilaterally permitted a million people to enter last year.

Poland, the largest among the former communist member states, has said the EU needs a new treaty, as the bloc had to reform to preserve its unity following Britain's decision to leave.